This invention relates to the field of telecommunications, and more particularly to a high availability local area network for a telecommunications device.
Many telecommunications devices include backplanes for transmitting digital information between components of the devices. For example, a telecommunications switching system might include a backplane for transmitting digital data representing voice signals between cards associated with incoming and outgoing ports. Typically, such a system would also include a mechanism to allow these cards to communicate with one another and to receive command, control, and administrative information from other components during operation of the system. Successful operation of the system in many instances depends heavily upon the ability of this communications mechanism to meet the often stringent availability, bandwidth, flexibility, and other requirements placed on the system.
As the telecommunications industry continues to dominate the growth of the global economy, meeting availability, bandwidth, flexibility, and other requirements placed on switching and other telecommunications systems has become increasingly important. However, previous communications mechanisms are inadequate to satisfy requirements placed on many systems, particularly those mechanisms intended for use within high availability backplane environments. A failure of such a communications mechanism or of a component intended to detect and handle faults associated with the communications mechanism may result in an very undesirable failure of the system as a whole. High availability may generally be considered as exceeding 99.999 percent availability, amounting to approximately five minutes or less of xe2x80x9cdown timexe2x80x9d each year. To achieve high availability, a system must generally be able to autonomously detect and handle certain faults, such as the failure of a card, without requiring immediate human intervention. Previous communications mechanisms often do not adequately meet this requirement. These and other deficiencies make such mechanisms inadequate within a high availability backplane environment of a telecommunications device.
According to the present invention, disadvantages and problems associated with communications in high availability backplane environments of telecommunications devices have been substantially reduced or eliminated.
According to one embodiment of the present invention, a telecommunications device includes a local area network with redundant first and second buses. Multiple cards coupled to the first and second buses communicate using the first bus. A first monitor coupled to the first and second buses detects a failure of the first bus and communicates a message indicating the failure using a data network. A second monitor coupled to the first and second buses may detect the failure of the first bus and may also communicate a message indicating the failure using the data network. If the first and second monitors receive the messages, the monitors cause the cards to communicate using the second bus. In other embodiments, the second monitor transmits a test signal using the first bus in response to the message from the first monitor if the second monitor has not detected the failure of the first bus. The second monitor may communicate the message to the first monitor in response to an improper test signal result, and the device may isolate the first monitor in response to a proper test signal result.
The local area network of the present invention provides a number of important technical advantages over previous communications mechanisms, particularly within a high availability backplane environment of a telecommunications device. The present invention provides multiple layers of fault protection, including both fault detection and autonomous fault handling, helping to avoid single points of failure, reduce down time, and satisfy high availability requirements. As a result of these and other advantages, the local area network of the present invention is well suited for incorporation in a wide variety of switching and other modern telecommunications devices. Other important technical advantages are apparent to those skilled in the art.